Opal and Bertrandite Optical Properties

Opal

Bertrandite

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Vitreous

1.2 Pleochroism

None

none.

1.3 Dispersion

NoneNA

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

TransparentAnthony et al, Handbook of mineralogy (2001)

1.5 Refractive Index

1.37-1.521.583-1.614

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21

1.8 Birefringence

Not AvailableNot Available

0 0.296

1.9 Clarity

Transparent

TransparentAnthony et al

Opal and Bertrandite Optic Character

Opal and Bertrandite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Opal and Bertrandite Physical Properties like crystallographic symmetry, pleochroism,etc. in the crystal. Some of the optical properties are refractive index, luster, optic character, pleochroism etc. Prominent among these is Opal and Bertrandite optic character. You might have noticed your gemologist rotating the gemstone while testing it. Rotating a gemstone along its optic axis helps in determining its optic character.

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Opal and Bertrandite Transparency

Similar to their colors, Opal and Bertrandite transparency can also be used as criteria for their primary identification. Although transparency cannot be the only criteria for gemstone identification, it can efficiently used in gemstone grading. Talking about their transparency, Opal is Translucent, Transparent and Transparent to translucent while Opal is Translucent, Transparent and Transparent to translucent in appearance.